bpf: rename bpf_compute_data_end into bpf_compute_data_pointers

Just do the rename into bpf_compute_data_pointers() as we'll add
one more pointer here to recompute.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>